Extended Data Fig. 8: Protein-protein interactions by FttA: effects of alanine substitution of FttA residues that contact RNAP or Spt5 in Tko FttA(H255A/H591A)–Spt4–Spt5–TEC⁴⁴ and Tko FttA(H255A/H591A)–Spt4–Spt5–TEC52⁵².

a, Effects of alanine substitution on FttA-dependent transcription termination and RNA cleavage, assessed in release assays with bead-immobilized promoter-generated TECs containing ³²P-5’-end-labelled RNA, detecting retained or released RNA by storage-phosphor scanning (methods as in ref. ¹ and Fig. 1b). P, pellet fraction; S, supernatant fraction. Top, gel image. Bottom, normalized efficiencies of FttA-dependent RNA cleavage [((RNA-cleavage efficiency)/(RNA-cleavage efficiency with wild-type FttA))100%]. Assays were performed twice, with consistent results obtained. For gel source data, see Supplementary Fig. 1. b, Effects of alanine substitution on FttA-dependent RNA cleavage, assessed in assays with TECs assembled on synthetic nucleic-acid scaffolds containing 44 nt fluorescein-5’-end-labelled nascent RNA, detecting intact and cleaved RNA by x/y fluorescence scanning (methods as in Fig. 1c). Top, gel image. Bottom, normalized efficiencies of FttA-dependent RNA cleavage [((RNA-cleavage efficiency)/(RNA-cleavage efficiency with wild-type FttA))100%]. Assays were performed twice, with consistent results obtained. For gel source data, see Supplementary Fig. 1.